A wire harness mounted on a vehicle such as an automobile is generally configured as an assembly obtained by bundling, for example, a plurality of sub-harnesses respectively prepared for each system. The sub-harnesses to be bundled are prepared according to various required specifications of the wire harness.
Specifically, there are a wide variety of electrical components to be mounted on vehicles corresponding to vehicle types, vehicle grades, and optional equipment (a sound system, a power window system, etc.) selected according to a demand of a vehicle customer (driver). Therefore, electrical wires or the like constituting a power supply line, a ground line, a signal line, and a communication line connected to the wide variety of electrical components are different. In order to cope with such differences in electrical wires, a bundle of electrical wires to be mounted standardly (standard electrical wire) is provided as a standard sub-harness for operating each of drive systems per drive system such as an engine and a motor. Further, in order to operate optional equipment or the like to be selectively mounted, a bundle of electrical wires to be mounted selectively and additionally (optional electrical wires) is provided as an optional sub-harness.
In recent years, application of Information Technology (IT) to vehicles such as automatic driving technology and external environment detection technology is rapidly advancing, and both standard electrical wires and optional electrical wires are tending to increase with the introduction of IT. That is, the number of types (kind) of sub-harnesses which is required to be prepared in advance has increased significantly when a wire harness is mounted on a vehicle.
Therefore, in order to prevent the increase in the number of types of sub-harnesses, it is known to construct a wire harness with a circuit substrate and a plurality of sub-harnesses by connecting the plurality of sub-harnesses to the circuit substrate and connecting the electrical wires of the sub-harnesses through a circuit pattern on the circuit substrate (see, for example, JP 2015-230873 A). In this wire harness, a circuit such as a branch can be provided in the circuit board for both the standard sub-harness and the optional sub-harness.
In the wire harness of JP 2015-230873 A, it is not necessary to provide a branch to both the standard sub-harness and the optional sub-harness by using the circuit board. Therefore, a shape of the sub-harness is simplified without branches and the entire system can be standardized.
Tastes and hobbies for each vehicle customer are extremely detailed and are more and more diverse. The increase in optional electrical wires to be selectively added depending on the type and grade of a predetermined vehicle may be significant. Therefore, a demand for standardizing only the optional sub-harnesses configured with optional electrical wires and reducing the number of types thereof is also expected in the future.
In order to meet such a demand, a large number of connection units for accommodating the circuit board described above are prepared to actively utilize the circuit board. Here, when the connection unit is disposed on a vehicle body, the circuit board of the connection unit is required to be connected to a grounding conductor formed on the vehicle body. However, when a large number of connection units including a circuit board are required to be disposed, work of disposing the connection units may be complicated.